Apparatus for condensing magnesium vapor



Oct. 22, 1935. F, R, KEMMER 2,018,266

APPARATUS FOR CONDENSING MAGNESIUM VAPOR Original Filed Jan. 12, 1934WITNE$$E$ INVENTOR.

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3 ATTORNEYS Patented Oct. 22, 1935 PATENT oFFIcE APPARATUS FORCONDENSING MAGNESIUM VAPOR Frank R. Kemmer, Larchmont,'N. Y., asslgnorto American Magnesium Metals Corporation,

Pittsburgh, Pa., a corporation of Delaware Original application January12, 1934:, Serial No.

Divided and this application November 20, 1934, Serial No. 753,883

8 Claims.

attained sustained commercial importance as applied to magnesium. Inthis process there is produced a mixture of magnesium vapor and carbonmonoxide gas, in equimolecular proportions, according to the equationgO+C Mg+CO. At elevated temperatures, for-example, above about 2000 C.,the reaction proceeds completely,

or substantially so, to the right, but as the temperature is loweredthere is a progressively greater tendency for the magnesium, both in thevapor and solid states, to be reoxidized by the carbon monoxide, i. e.,decrease of temperature causes the reaction to proceed toward the leftin the foregoing equation. It is only when the solid has been cooled toquite low temperatures that the reoxidation becomes so slight as to beunimportant. This situation has engendered grave difiiculties in thecondensation of magnesium from the reaction products because thereoxidation of the magnesium vapor has been so serious as to preventeconomical practice from a commercial standpoint. Such reoxidationcontaminates the magnesium with oxide, and it represents an added costburden. In consequence of these and other factors magnesium has for manyyears been produced commercially by electrolytic methods.

It is among the major objects of this invention to provide an apparatusfor condensing magnesium vapor, especially from a mixture thereof with agas reactive therewith, which provides satisfactory condensation of thevapor to the solid state, effectively prevents reaction between themagnesium and accompanying gas, is simple and may be easily practiced inconnection with desired electrotliermic procedures and apparatus.

The invention may be described in connection with the accompanyingdrawing which schematically represents a longitudinal sectional viewthrough an apparatus suitable for use in the practice of the invention.

The present invention is predicated upon the fact that the prejudicialreaction of magnesium vapor with a reactive gas, for example, with car-'bon monoxide gas, may be effectively prevented by cooling the mixtureof'vaporand CO gas from a temperature at which such reaction does not 5occur, so rapidly to such a low temperature as substantially to precludethe reaction. In my cofi'nding application Serial No. 664,932, filedApril 7, 1933, I have described and claimed a method of condensingmagnesium vapor according to which the vapor is impinged against amoving filmfor curtain, of liquid inert to magnesium, preferably a. thinfilm of liquid flowing over a stationary cooled surface. The presentinvention makes use of the gist of that disclosed 15 in my aforesaidcopending application, together with certain other features.

In accordance with the present invention a stream of magnesium vapor-iscaused to impinge upon a cooled surface provided with a layer, e. g., 20a film, of liquid inert to magnesium and the surface is continuouslymoved to present fresh cooled areas and fresh liquid for continuouslymaintaining condensation. The invention is applicable th thecondensation of pure, or substantially pure, 25 magnesium vapor, butparticularly is it applicable to the condensation of magnesium vaporfrom a mixture thereof with a gas reactive to magnesium, such as carbonmonoxide. In the latter aspect of the invention the mixture is presentedto the condensing operation at a temperature such that reaction does notoccur, and heat is abstracted from they cooled surface at a rate such asto cool the magnesium so rapidly through the critical temperature rangeas to prevent reaction of the vaporous and condensed magnesium and thegas and to bring the solid to a temperature at which such reactionproceeds at a negligible rate.

In the preferred embodiment of the invention 40 the stream of magnesiumvapor is caused to impinge from a fixed point upon a surface of arotating metallic drum the lower portion of which rotates in a bath ofsuitable liquid. Advantageously the drum is mounted so that its (5 endsrotate in a plane normal to the direction of flow of the Mg vapor, theend adjacent the vapor stream forming the condensing surface. Thecondensing surface of the drum is cooled interiorly thereof by anysuitable means. Thereby 50 there is continuously presented to theimpinging stream of magnesium vapor a fresh, cooled condensing surfacewith fresh liquid thereon, and by suitable provision for adequateabstraction of heat, through the interior cooling, and if desired posesof illustration, but not by way of limitation.

Having reference to the drawing, a mixture of magnesium vapor and COissues in a stream from a port I in a wall of an electricreduction-furnace 2, the mixture being produced at a temperature atwhich reoxidation does not occur, e. g., 2000' C.

or higher, and it impinges against the end sur-' face 3 of a drum 4-journalled for rotation by any suitable means, not'shown. As shown in.the drawing, the drum is mpimted to bring its condensing surface asclose as practicable to the source of the vapor-gas stream, and ifdesired it may be adiustably mounted to vary the distance according toneed. 1

The drum is cooled'interiorly in accordance with the invention, andinfthe embodiment this is accomplished by mounting the drumconcentrically on the end of a hollow trunnion 5 of relativelylargediameter through which there extends a conduit 8 for conveying water toa spray head I facing condensing surface, 3 against which it distributescooling water. Trunnion .5 is conveniently mounted in bearings I. Thewater collects in-the bottomof the drum and overflows through thetrunnion I in the annular space surrounding conduit '8. The trunnion isrotated, to rotate the drum, by suitable means, not shown.

The lower portion of the drum projects into a bath of a suitable liquidll, so as to be continuously bathed therein, and as the drum rotates itcarries a film of liquid ll distributed on condensing surface 3 upwardlyinto the region of the impinging vapors, and likewise continuouslyreturns the liquid to the bath. Any suitable liquid which is inert tomagnesium under the conditions of operation may be used, althoughadvantageously a hydrocarbon oil, such as kerosene or the like, is used.Such oils not only aiIord desirable properties for condensation, butalso provide a protecting film over thecondensed particles, and theyalso are adapted to provide eiiective protective atmospheres in otheroperations.-

Access of air to the vapors is, of course, to be avoided. To this endthe apparatus is enclosed in a housing I I whose bottom and side wallsmay, if desired, cooperate to form, in effect, a tank for holding liquidIll. The residual gas is withdrawn through a pipe I! provided with adamper l3 for regulating gas flow, to provide a slight back pressure andthus prevent entry of air into the housing. To further exclude air,trunnion 5 is mounted in a suitable packing gland ll associated with-wall Ila of the housing.

In the practice of the invention the stream of Mg vapor and CO gasissues from port I and impinges against surface 3 ,where the magnesiumis instantly condensedand cooled to a temperature at which 00 has noeffect upon it, e. g., 150 C. or

lower. The necessary cooling may be eifected wholly or primarily throughthe cooling water projected against the inner side of the condensingsurface from spray head I, the cooling effect being controllable throughthe volume of water used and by supplying it in a refrigerated state ifneed be. The coolingeflectmay be augmented by cooling liquid II, as byrefrigerating coils, not shown, disposed in the bath, or in a mannerpresently to be described.

In order to separate any solid matter from the 5 residual gas prior toits escape, .there may be provided one or more baifies 'llb arranged infront of the gas outlet to conduit l2. Solids carried by the gas thusare separated by impingement on the baifie, fall into the bath, and 10are recovered together with magnesium con-- densed on drum face I.

. The magnesium vapor is condensed to the solid state and in part fallsinto the bath and in part is carried into it by the film of oil adheringto ll surface where it is washed off. The condensed metal collectedinthe liquid bath is then recovered, for instance, by withdrawing themetal in suspension in the oil through a conduit II and separating thetwo materials, as by means of a 20 filter press, not shown, the cleanoil being returned for further use through another conduit I. If

, desired the oil may be refrigerated in this operation, for instance bypassing it through suitable refrigerating means after it has beenfreedfrom e metallic magnesium which it carries.

Oxidation of the metallic vapor due to the oxy-' gen ofthe atmosphere isprevented by housing H which acts to prevent air from reaching the hotvapor. The carbon monoxide gas remaining after condensation escapesthrough a pipe II, the

opening being controlled by damper It so that there is always sufiicientcarbon monoxide pressure within the housing to prevent inward seepage ofair.

It will be recognized that the invention is not restricted to theparticular apparatus shown, nor to the condensationof magnesium vapor inadmixture with carbon monoxide gas, but that it is applicable not onlyto condensation of the 0 metallic vapor from mixtures with otherreactive gases, but also to the condensation of substantially puremagnesium vapor, for example, derived from a distillation process.

This application is a division of my copending application Serial No.706,358, filed January 12, 934. entitled Method of and apparatus forcondensing magnesium vapor.

According to the provisions of the patent statutes, I have explained theprinciple and operation of my invention, and have illustrated anddescribed what I now consider to represent its best embodiment. However,I desire to have it understood that, within the scope of the appendedlaims, the invention may be practiced otherwise than as specificallyillustrated and described.

I claim:

1. Apparatus for condensing magnesium vapor, comprising arotatably'mounted drum, means operably connected to the drum forrotating it,

means for directing a stream of magnesium vapor against a surface of thedrum, 'means for providing said surface with a film of liquid inert t0magnesium, means for cooling said surface interiorly of the drum, andmeans for collectin the magnesium condensed on the drum.

2. Apparatus for condensing magnesium vapor. comprising a housing, adrum rotatably mounted therein, means operably connected to the drum 7for rotating it, means for directing a stream of magnesium vapor withinsaid housing against a surface of the drum, means for providing saidsurface with a film of liquid inert to magnesium, means for cooling saidsurface interiorly of the (I drum, and means for collecting themagnesium condensed on the drum.

3. Apparatus for condensing magnesium vapor, comprising a housing, adrum rotatably mounted in the housing, means operably connected to thedrum for rotating it, means for directing a stream of magnesium vaporwithin the housing against a surface of the drum, a bath of liquid inertto magnesium through which the lower part of said drum moves, means forcontinuously circulating a cooling fluid through the drum, and means forcollecting the magnesium condensed on the drum.

4. Apparatus for condensing magnesium vapor, comprising means forforming and directing a stream of magnesium vapor, a drum mounted torotate on an axis parallel to that of said stream and to present an endthereof adjacent said means for impingement of said stream thereon, ahousing enclosing said means and drum, means operably connected to thedrum for rotating it, a container of liquid below said drum throughwhichits lower portion moves, means for circulating a cooling fluidthrough the drum, and means for collecting magnesium condensed on thedrum.

5. Apparatus for condensing magnesium vapor, comprising a source ofmagnesium vapor, a housing associated with said source to prevent accessof air into the housing, a drum rotatably mounted in the housing, meansoperably connected to the drum for rotating it, means for directing astream of magnesium vapor from said source into said housing against asurface of said drum, a container of liquid inert to magnesium disposedwithin said housing below said drum for rotation of the lower portion ofthe drum therethrough to provide said surface with a film of saidliquid, and means for cooling said surface interiorly of the drum.

6. Apparatus for condensing magnesium vapor, comprising means forforming and directing a stream of magnesium vapor, a drum mounted torotate on an axis parallel to that of said stream and to present an endthereof adjacent said means 5 for impingement of said stream thereon, ahousing enclosing said means and drum to prevent access of air, meansoperably connected to the drum for rotating it, a container of liquidbelow said drum through which its lower portion moves, means forcirculating a cooling fluid through the drum, and means for collectingmagnesium condensed on the drum.

7. Apparatus for condensing magnesium from a mixture of magnesium vaporand carbon monoxide, comprising an electric furnace adapted to producesaid mixture and having an opening in one wall for passage of themixture therethrough,

a drum rotatably mounted to present a surface adjacent said opening forimpingement of said mixture thereon, means operably connected to saiddrum to rotate it, a container of liquid inert to magnesium mountedbelow-said drum for rotation of the lower portion of the drumtherethrough to provide said surface with a film of said liquid, meansfor cooling the drum interiorly,

a housing enclosing said drum and opening to prevent access of air, andmeans associated with the housing for withdrawing carbon monoxideremaining after condensation of magnesium vapor admixed therewith.

8. An apparatus according to claim 7, said drum presenting an endsurface to said opening for impingement and condensation of magnesiumvapor thereon.

FRANK R. KEMMER.

